JavaScript Array concat() method : The concat() method is used to join or combine the two or more arrays. It doesn't change the original array. It return the new array having all the elements of ...

.concat() takes an existing array, adds a value to it and returns a new array it takes a copy of the original array, adds to it any parameters passed and returns a new array. .concat() is the ...

既存の配列を変更せず、新しい配列を返します。 https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/concat push ...

The concat() method of {{jsxref("Array")}} instances is used to merge two or more arrays. This method does not change the existing arrays, but instead returns a new array.